


the oath

by Littleyue



Category: Undertale (Video Game), back when they lived on the surface (fandom), reapertale(fandom)
Genre: Alternate Universe - Royalty, Angst and Hurt/Comfort, Arranged Marriage, Assassination Attempt(s), Enemies to Friends to Lovers, Implied/Referenced Rape/Non-con, Implied/Referenced Torture, Kidnapping, M/M, Multi, Past Alcohol Abuse/Alcoholism, Past Drug Addiction, Self-Harm, Witchcraft, theres a lot of referenced things
Language: English
Status: In-Progress
Published: 2021-02-14
Updated: 2021-02-20
Packaged: 2021-03-14 09:20:25
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 3,028
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29416278
Author URL: https://archiveofourown.org/users/Littleyue/pseuds/Littleyue
Relationships: Asgore Dreemurr/W. D. Gaster, Death/Sans (Undertale), Grillby/Muffet (Undertale) (past), Mettaton/Sans (Undertale), Muffet/Sans (Undertale) (past), Sans/Sans (Undertale), sans/mettaton/death
Comments: 4
Kudos: 8





	1. the arrival

**Author's Note:**

  * For [gaylie](https://archiveofourown.org/users/gaylie/gifts), [comic4244](https://archiveofourown.org/users/comic4244/gifts).



“It’s time to get up”

The voice was soft, almost as if he didn’t want to wake up the sleeping figure. His footsteps echoed throughout the room as he cautiously approached the bed. Under normal circumstances, the fire elemental wouldn’t bother to wake the prince.

However, today the prince is expected to greet one of the most dangerous and infamous royal family's. It was Grillby’s job to make sure that the prince was presentable. If only sans hadn’t made that job so difficult.

Grillby let out a loud sigh as the prince pulled his white silk sheets over his head and turned away from the elemental.

“Sans, wake up. They are going to arrive in a few hours,”

There was a pause.

The room was mostly silent as the prince slowly sat up in their bed, looking miserable. Grillby let out a sigh he hadn’t been aware that he was holding as he rubbed the prince’s back.

Sans said nothing as Grillby began bringing clothes for sans to wear. Only glaring at the bed as if it had been the one to wake him. The clothing itself was… formal. A white vest with a royal blue tunic that had golden edges that shined in the morning sun. Charcoal black pants with shiny black leather boots, and an overcoat with the family crest on the upper arm.

As much as sans didn’t want to wear the clothing, it wasn’t the worst thing they have forced him to wear. Usually, the clothing chosen for a formal event would be extravagant, having layers upon layers of blue, gold, and white clothing.

Sans mumbled a quick “thank you” before moving to put on the outfit, Grillby letting out a hum in acknowledgment.

“I’ll be waiting outside. Let me know if you need anything.”

The young prince stays quiet, slouched over as Grillby leaves the room

-

Sans footsteps echo throughout the empty halls as he made his way outside. The servants and maids had been told to avoid the new royals for their own safety. The eerie silence made his thoughts race as he fumbled with the sleeve of his coat.

What would they be like? Would they like him? Are they as violent as the stories made them out to be?

He’s heard the tales of these tyrants. All the towns and villages they’ve taken over the years, the harsh punishments for seemingly harmless crimes, acts of aggression towards any suiter who dared to ask for the son’s hand in marriage.

Sans let out one last sigh before opening the door at the end of the hallway. Hissing at the bright light before getting a bear hug from Papyrus.

“SANS! THERE YOU ARE!!! YOU’RE LATE”

Papyrus lifted his older brother off the ground as he swayed sans’ limp body back and forth. Gaster watched with a smile on his face from the garden as sans chuckled.“I am? Could’ve sworn I was told to sleep in”

“NO, YOU WERE NOT”

“Really? I remember dad coming in and telling everyone to sleep in and stay in their rooms”

“THAT WAS FOR THE WORKERS AND YOU KNOW THAT!”

“Nah, I heard it from three rooms down. If I heard it, it was meant to be”

A smirk formed on Gaster’s face as he looked towards the gardener holding a pot of basil.

“you can just drop that wherever”

Papyrus looked down at his brother and watched the fear in sans’ eyes “I HEARD IT FROM THE DOOR. IT WAS MEANT TO BE!”

As the arms that held sans let go, he saw his life flash before his eyes. Every mistake, every happy moment, every time he’s ever pranked his brother. This was his sick revenge. Being tossed from the safety of his brother's arms. Betrayed by his own flesh and blood. Truly a death that would shake the kingdom to its very core.

Sans sat there and died dramatically as papyrus tried to revive his brother.

“SANS YOU CAN’T BE DEAD! THEY ARE COMING!!”

“Sorry I can’t marry. I’m dead”

“SANS NO”

“Sans yes”

Papyrus grabbed his brother by the arm and forced him to stand. Unfortunately, he had to live another day. After brushing himself off, they could hear a voice in the distance announcing the royals.

Quickly, Gaster got everyone into position as the black, and gold carriage arrived. Once it stopped, two heavily armed servants walked in front of the carriage and announced the tyrants themselves.

The Grims.

Once the door opened, two figures in black hoods walked out. Both looking towards the ground as the king himself came out. Dressed entirely in black and gold. All three seemed armed with the same weapon, the kusarigama. Aster pulled back his hood as Gaster attempted to bow, only stopping by aster giving him a hug.

“It's so good to see you again old friend!”

Gaster laughed as he pulled back from the hug

“Its nice to see you too Aster, though i wish it was under better circumstances”

“Oh nonsense! Your son is arranged to become part of my family! I can’t imagine a better scenario! Now, lets get down to business shall we?”

Both sans and papyrus stood there in shock of the situation. This was the tyrant? The one who has leveled entire kingdoms for just looking at them wrong? The one who would actively torture anyone who dared to cross him? This was the legendary Meister Aster Grim??

Meister seemed to notice the boy's shock as he gestured towards them. Gaster laughed as he looked down at his boys.

“I would like to introduce you to my son’s. My eldest, sans, and youngest papyrus”

Sans quickly nodded as he looked towards the hooded figures in the back

“Why! It's an absolute pleasure to meet you sans! This is my son, Death”

Death visibility cringed when Meister told him to hold his hand out for sans. Sans also cringed as he gently held Death’s clawed hands and brought it up to his mouth to kiss it. Both parties quickly pulled their hands back after it was done.

“And my other son, Reaper”

Reaper nodded quietly towards papyrus as papyrus waved.

Meister turned his attention back on sans and quickly bended down to his level with a big friendly smile on his face. Sans saying nothing as beads of sweat began to form. Before anyone could react, meister gripped sans throat tightly. Everyone tensing up as his smile fell from his face, sans hands helplessly holding on to Meisters wrist. Leaning in slowly meister glared at sans with a face that could only be his one and only warning.

“Watch yourself. The moment you begin to even think about treating my son poorly, I assure you, my friendship with your father will do absolutely nothing to save you. Nothing, and I mean nothing, will save you from my wrath. Do you understand?”

Sans hands began to tremble as he looked over at his brother and dad. Gaster was more scared than he's ever seen him as he held his brother's arms to keep him from intervening. The prince nodded. He was quickly dropped as meister stood up. Already back into a happy mood.

“Good! Now why don’t you both show one of my sons around the palace while I speak with Gaster?

They quickly nodded as they offered to show the grims around. Papyrus assured sans that he could handle showing Reaper around. his voice dropping down to a whisper

“I’m not the one that he threatened. Be careful”

Sans rubbed the front of his neck as he turned to death.

“You uh, you ready..?”

Death shrugged

“Yea’ jus’ need ta mer.. .merv..Mer’ve..inta mah room.” death tapped some small boxes.

Sans stood there confused for a moment until he saw the boxes.

“O-oh! You need t-to move your boxes. Yea, don’ worry I-I gotcha.”

Sans cautiously went over to pick up the boxes, hands still trembling as he looked over at meister, watching him closely. Sans let out a small breath as he looked over at death

“Alright, just follow me”


	2. Chapter 2

The tour itself was… painfully silent

No matter what Sans tried, Death refused to say a word. The only response Sans had gotten throughout the tour was a small hum when shown the kitchen. After thirty minutes of absolute silence on Death's end, Sans decided to just bring Death to his room.

Both parties let out a sigh of relief as soon as they made it to Death's new living quarters. Sans sets down his new partner's box as he opens the golden door. The room itself was… extravagant.. to put it nicely. 

There was an aureate light coming from the massive window that looked down onto the village. The family crest casting a shadow unto the newly finished parquet floor. Walls an off white as they reflected the light off of the large golden pillars that were in each corner of the room. A vanity with a massive mirror pointed towards the softest looking bed either party has ever seen.

Several paintings hung off the walls, many of them of parts of the kingdom. A lavish chandelier covered head to toe in precious gems.

Both Sans and Death froze in place as they stared into the room. No one dared to say a word as they glanced at each other.

Sans burst into a fit of laughter as Death stood there stunned. He knew that the room would be fancy, but.. This?? This was nicer than his room. Not that he minded. He honestly cared little about how his room looked.

But… Death's face looked disgusted by the room. 

“oh, wow.. this is.. wow.. ya good..?”

Death nodded as they walked into the room to set their boxes down. “tank ya. M’ good fer now. Jus’ gotta… unpack”

Quickly, Death began cutting open his boxes and looking around the room. From what Sans could see several bagged up herbs, small glass jars, and several gems.

Sans stayed there for moment in confusion as Death brought one of his blankets, climbed on top of the vanity and draped the blanket over the mirror

“huh.. do.. do you need help wit’ unpackin’?

Death glared at sans as they climbed down the vanity. He can manage the room just fine without help. He doesn’t need this fucking prince’s help. Choosing to ignore Sans, he goes back to work on opening his boxes.   
Sans rolled his eyes then pushed himself off of the door frame to help with the boxes much to Death’s dismay. As Sans opened one of the boxes they sat there looking confused.

The box contained mostly herbs, packaged and labeled next to different colored candles. Next to the candles were some cards neatly wrapped inside a mortar with a pestle right next to it.

What was this all for? Some of the herbs were almost out. The lavender, rosemary, and thyme were nearly completely gone. Before Sans could grab one of the bags Death snatched it out of the box

“why ‘re ya still ‘ere? Don touch mah things. I dun ‘ave anymer” teeth bared at the prince

Sans turned to Death with wide eyes “relax? m’ just tryna help y’ out!”

“dun need yer fuckin’ ‘elp! Now fuck off!” 

Grabbing the prince by the wrist, Death dragged him out of the room.

“Gonna make somethin’ clear. I dun fuckin like ya. Jus cause were stuck in this situation doesn’ mean m’ gonna be nice ta ya”

Pushing Sans out the room, Death slammed the door in his face. Sans stood outside of the door for a moment before letting out a muffled frustrated groan. It was fucking clear that Death wasn’t planning on just tolerating the skeleton.

Oh well. He could give less of a fuck if Death didn’t like him. He didn’t care much for Death either. 

However   
,  
He was intrigued. Afterall, it's not everyday you get to meet the son of the most infamous tyrant.

-

Death had spent the rest of the afternoon arranging his room in a way that felt more like home. As he stretched a small knock came from the door. Groggily the prince made his way out of the room only to be met with one of the servants.

“H-hello prince, i apologize for the disturbance but the king has invited you to a welcoming d-din-”

Without a second thought Death slammed the door in the servants face. The last thing he wanted was to be mingling with the king. Another knock came from the door, this time louder. With a groan Death opened the door ready to glare at the servant only to be met with the other prince. Ah, papyrus

“HELLO! I’M PAPYRUS AS YOU’VE HEARD BEFORE!”

The young prince gave a quick bow before giving Death a big warm smile

“HOW ARE YOU DOING SO FAR! DO YOU LIKE THE ROOM!”

Death looked at papyrus in mild surprise as they looked past Death into the room. 

“..uhh.. M’ doin’ a’right..da room s’ nice.. I guess.”

“THATS FANTASTIC!! I HELPED DESIGN THE ROOM AS SOON AS WE HEARD YOU WERE COMING!”

As papyrus looked into the room once more he frowned at the sight of the window and mirror being covered completely by a blanket, the bed no longer in the spot it once was, now pushed so the head will face west when sleeping and the rearranging of pictures.

“IF YOU DIDN’T LIKE IT YOU COULD’VE JUST TOLD ME!! I’LL BE MORE THAN HAPPY TO HELP YOU WITH YOUR ROOM!”

“O-oh.. ya dun gotta he-”

Before Death could finish papyrus made his way inside the room with a big smile on his face. “SO DO YOU NOT LIKE MIRRORS?”

“I.. I do. Jus’ nah facin my bed”

“GOT IT! ANYTHING ELSE?”

“Uhh.. the window..? S’ too bright”

Papyrus just stood there waiting for Death to continue before moving.

“S’ a lil.. Bright.. Not like ‘ome i guess. My room ‘as dark.. An’ cozy.. Nah so..” Death waved his hand around papyrus the idea. It's just.. So different from his place. Knowing he was going to stay here for the rest of his life made him…..nevermind

Papyrus seemed to get the idea on what Death meant, quickly getting out a notebook to write what Death needed. 

“ALRIGHT! I’LL GET EVERYTHING READY! IS THERE ANYTHING ELSE?”

Death shook his head with a confused look on his face. Another knock on the door caught both of their attention. When Death opened the door, there was no one there. The door next to his quickly closing as Death looked on in confusion. On the ground was a bundle of lavender on the floor. Without a word, Death picked the plant up. Staring in awe as he ran over to the fireplace, quickly lighting a flame as he set up an area a little farther away to dry the plant. 

Taking three stems from the bunch and setting it aside, Death wrapped the remaining bunch up in ribbon while leaving some ribbon for him to place it upside down. Quickly finding a dark area within range of the fireplace's heat, he set a blanket under the plants for any parts that may fall.

Death grabs the remaining bunch and walks over to papyrus “‘ere do ya find dis?”

Papyrus looks at the plant for a moment before shrugging “I DON'T KNOW! WE DON’T HAVE THOSE IN THE GARDEN.”

Death nods then runs out of the room, leaving papyrus standing there by himself. Guess this will be a good chance to decorate Death’s room.

-

Death was banging on the door next to his waiting for someone to answer. He tried the doorknob only to find that whoever locked it. They quickly turned their attention to a servant who was walking down the hall. Death quickly stormed towards them and held up the flowers to the now terrified maid. 

“‘Ere do ya find dis?”

“I-I-I don't know! I-I dont work outside of palace walls! M-maybe you could a-ask one of the guards?? W-where did you get that o-one?”

“I’ was left fer me by da door. Whoeva did it's’ behind dat door”

Pointing towards the door he has been attempting to open. The servant's eyes went wide in surprise as she looked back at Death “y-you mean the prince? H-he's in the kitchen!”

Death paused. The prince? Is this his way of trying to make his way into Death’s arms? Why would he…

Shaking his head, Death walked away from the maid and made his way to the kitchen. It took awhile for Death to find, but once he spotted the prince, he made sure to let them know that Death was coming for him. 

Sans sat with Grillby, talking about nothing in particular when Grillby spotted a pissed off looking Death coming straight for Sans. Before Grillby could do anything, Death grabbed Sans by the shoulder and spun him around.

Shoving the flowers in his face, his teeth bared. “‘Ere did ya find dis?”  
Sans looked at Death in shock and confusion before the question finally registered. “T-the flowers? I found ‘em in the meadow. Kinda close to tha forest just outside of town. y-y’ looked like y’ needed some..”

Death growled as they continued to glare at Sans “‘f ya think tha dis s gonna make me like ya de-”

“what no! i just wanted to help you out s all! ..jus’ figured if i helped ya out maybe ya wouldn’ be so.. pissed off? this .. isn't a situation either of us wanna be in. might as well make it a tolerable one.. ya know?”

For a moment, Death’s expression softened before it went completely blank. 

“plus it's not everyday you get to meet the son of a tyrant soo..” 

With a sigh Death nodded and made his way back to his room

“Got i’. T’anks” 

Sans sighed as he watched Death walk off.

\- 

In the halls, Death twirls the stems in between his fingers, looking down at them as the remaining light from outside shines on them.

A small smile growing on his face as he walks the halls.


End file.
